Control of wing flaps on aircraft



Dec. 13, 1938. w. D. L. THEED 2,140,095

CONTROL OF WING FLAPS 0N AIRCRAFT Filed Nov, 27, 1936 2 prmxwsy PatentedDec. 13, 193$ UNITED STATES PATENT OFFICE William Denis Learoyd Theed,London, England, assignor to Sir George Godfrey and Partners Limited,London, England, a company of Great 7 Britain Application November 27,1936, Serial No. 113,079 In Great Britain December 5, 1935 1 Claim.

wing flaps on aircraft and has forits object to provide. controlapparatus which,'while being simple in construction, light and compact,will obviate or reduce. the effort which-the pilot would otherwise becalled upon to exert when moving the flaps into the operative position.

' According to the present invention the wing, flap or flaps areactuated by power derived from the suction of the engine or power unit.

The apparatus preferably comprises a servo cylinder containing a pistonoperatively connected to the flap or flaps, and a control valve wherebycommunication can be established between the servo cylinder and theinduction system of the engine or power unit. Means may also be providedwhereby the flaps are normally held inoperative or moved into theirinoperative position by power derived from the induction of the engineor power unit.

The servomotor may comprise a cylinder containing a double-actingpiston. connected to the flap or flaps, the said valve controllingcommunication between the induction system of the engine or power unitand the servo cylinder on oppositesides of the piston so that the flapsare wing flap A, hinged at the trailing edge of the wing A is connectedto a torquetube B having a crank B secured thereto. The crank B isconnected to the rod-C of a single acting piston C arranged within aservo cylinder C which is mounted to pivot on a fixed bracket C. The

piston C is biased by a compression spring C" which tends to maintainthe crank B in the position shown in full lines and corresponding to theraised or inoperative position of the flap A.

A flexible tube D leads from the cylinder C to a casing D of a three-wayrotary valve D which is under the control of the pilot, this valve beingpreferably loaded by a spring (not shown) which tends to retain thevalve in the position shown. The valve casing D has three ports, namelya port D leading to the flexible tube D a port D open to the atmosphereand a port D leading This invention relates to the control of thethrough a'pipe E to a suction reservoir E. The reservoir has anon-return valye E controlling a port through which air can be drawnfrom the reservoir through a pipe E communicating with the inductionpipe E of the engine indicated at E.

When the valve D is in the position shown the servo cylinder Ccommunicates with the atmosphere through the ports D and D so that theby the crank B the axis of the spring B lying above the axis of thetorque tube B. When the pilot wishes to render the flaps cperativeheturns the valve D in the direction shown by the arrow, thereby cuttingoff communication between the ports D and D and establishingcommunication between the ports D and D The suction thus produced in thecylinder C, due to the depression in the reservoir E, moves the piston Cagainst the action of the spring C and turns the crank B towards theposition indicated at B. axis of the spring B normally lies above butadjacent to the axis of the torque tube B the spring B will not beappreciably extended during the initial downward movement of the flap Aso that though the spring will normally assist in maintaining the flap Ain its raised or inoperative position it will not materiallyadd to theload on the servo-pistonC when this turns the flap A towards the fullyoperative position indicated By suitable manipulation of the valve 1.:the degree of the depression produced within the cylinder can bemodified to bring the piston C and therefore the flap A to the desiredposition, the valve D being then retained in an intermediate positionwherein all the ports D,'D* and D" are closed. The'spring C and thedepression Since the 7 within the'cylinder C then balance each other sowith the reservoir E when the valve F is in the position shown in thedrawing, so that the flap will be held in its inoperative position bythe auxiliary servomotor, whose cylinder is brought into communicationwith the atmosphere when the valve D is turned to bring .the ports D andD into communication.

Figure 2 illustrates another arrangement in which the piston'C is doubleacting within the cylinder C opposite ends of which communicate throughflexible pipes F and F with the casing G of a four-way rotary valve G.The valve casing has four ports, namely the ports G and G communicatingwith the pipes F and F, a

port G open to the atmosphere and a port G communicating through a pipeE with a suction reservoir E as described with reference to Figure 1. I

Under normal conditions the valve G is held in the position shown, say,by a control spring, so that the cylinder C on the left of the pistonCcommunicates with the atmosphere through the ports G and G, the part ofthe cylinder C on the right of the piston C communicating through theports G and G with the suction reservoir E. The crank B is thus held inits raised or inoperative position by the suctio derived from theengine.

When the pilot wishes to render the flaps operative he turns the valve Gso as to cut off communication between the ports G and G and between theports G and G, but to establish communication between the ports G, G andbetween the ports G and G. The part of the cylinder C to the left of thepiston C is thus brought intocommunication with the suction reservoir Ewhilst the part of the cylinder C to the right of the piston C isbrought into communication with the atmosphere. 'The piston Cistherefore moved to the left so as to move the flap A from theinoperative position towards the operative position indicated at A.

By suitable manipulation of .the' valve G the degree of suction on theopposite sides of the piston C can be determined so as to bring thepiston C into, and retain it in, the desired position. The flap A canthus ,be brought to any position between the fully raised or inoperativeposition and the fully lowered or operative position A.

Yet a further construction embodying the invention is shown in Figure 3in which the servo cylinder C, similar to that described with referenceto Figure 1, communicates through a flexible pipe H with the casing H ofa piston valve H. The casing H has two ports H and H come municatingrespectively with the flexible pipe H and a flexible pipe E leading to asuction reservoir E similar to that described above. The casing H isalso furnished with ports H open to the atmosphere.

A control lever J, accessible to the pilot, is

. connected through a rod J to the piston valve H. A spring K bears atone end against the casing H and at theother end against a flange ,1formed on the valve H, the spring K thus urging the valve H? to theright as shown in the drawing so as to tend to maintain the conicalsurface K of the valve on a cooperating seating surface formed withinthe casing H. With the.

'between the ports H and H spring B, now holds the flap A in the raisedor inoperative position as shown.

If the flap A is to be rendered operative the pilot moves the lever J inthe direction of the arrow so that the conical surface K of the valve His moved off its seating surface and communication between the ports Hand H is cut off prior to communication being established The resultingsuction in the cylinder C moves the piston C to the left as viewed inthe drawing and thus turns the flap A down towards" the positionindicated at A. The crank B,-"moving in the clockwise direction,transmits movement through a rod L to the casing H and thereby causesthe valve H to close the port H thus cutting off communication betweenthe cylinder C and both the ports H and H The piston C is thus broughtto rest within the cylinder C at a position corresponding to the degreeof movement of the lever J, that is to say corresponding to the requiredangular downward movement of the flap A. Should the air flow acting onthe flap A tend to turn this from the desired position of adjustment inthe counterclockwise direction, the crank B will act through the rod Lso as to move the casing H to the right and thus temporarily establishcommunication between the ports H and H thereby increasing the suctionwithin the cylinder C and restoring the flap A to the desired position.The restoration of the flap A to the desired position will again,movethe casing H to the left so as to cause the valve H to close the port HIf now the pilot wishes to lower the flap A still further he moves thelever J further in the direction of the arrow whereby the valve Hestablishes communication between the ports H and H and the piston C ismoved further to the left until the resulting clockwise movement of thecrank B has moved the casing H so as to cause the valve H to close theport K5 With this arrangement, therefore the pilot can set the flap A atany one of several operative positions between the inoperative or fullyraised position .and the fully operative position indicated at A.

For this purpose the lever J may be arranged to cooperate with apositive latch or gate J whereby the lever can be set and retained inany "one of several positions. Alternatively means a wing or wings ofthe craft, the suc ion reservoir having a capacity sumcient to providethe necessary power for operating the flaps several times.

If desired means may be provided whereby movement of the lever or thelike, whereby 'the valve is controlled by the pilot, be and the nor-'mal range necessary for the cont c1 of the servomotor will causemovement to be mechanically transmitted to the flap or flaps directlyfrom the lever. To'this end the lever may be connected through a lostmotion coupling to a mechanical system of levers or cords for operatingthe flap or flaps, the arrangement being such that during movement ofthe lever through its normal range through the mechanical system to theflaps. 76

. secure by Letters Patent is:-

With a view to avoiding an undesirably long travel of the valve undersuch conditionsthe valve may be connected through a lost motion device,such for example as a compression spring, to the pilots lever. I

It will beunderstood that the constructions above described are given byway of example only and that details may be modified. Thus, for

example, instead of the se'rvomotor being operated by the suctionderived from the induction side of the engine itself, the servomotor maybe operated by the suction on the intake side of a supercharger.v

What I claim as my invention and desire to In apparatus for controllingthe wing flaps of aircraft, in combination, a power unit including aninternal combustion engine, at least one movable wing'fiap, a pneumaticservo cylinder, a

conduit communicating with the said. servo cylinder and subjected tosuction produced by the servo cylinder, interconnecting means betweenthe piston and the said flap, a valve controlling communication betweenthe servo cylinder and the said suction conduit and comprising acylinder having at least three ports, a plunger movable within saidcylinder, one of which is open to the atmosphere while the other twocommunicate respectively with the said suction conduit and with theservo cylinder, a manually operable control device connected to thevalve plunger, said plunger having free range of movement within saidvalve cylinder equivalent to the full range of movement of said controldevice and interconnecting means between the valve cylinder and thesaid'flap, whereby movement of the flap, due to air pressure thereonfrom a desired position causes movement of the valve cylinder relativelyto the valve plunger, thereby automatically causing operation of theserv0-- motor in a sense tending to restore the flap to and retain it inthe said desired position.

WILLIAM DENIS LEAROYD THEED.

